Field of the Invention
The invention relates to an arrangement for providing a vehicle with electric energy, wherein the arrangement comprises a generating device adapted to generate an alternating electromagnetic field for inducing an alternating electric current by magnetic induction in a corresponding receiving device. The arrangement comprises a base to which the generating device is attached. The base defines a vehicle location where a vehicle may be placed or may travel through. Furthermore, the invention relates to a method of manufacturing the arrangement and to a method of providing a vehicle with electric energy using the arrangement.
Description of Related Art
In particular, the present invention can be applied to any land vehicle, in particular track bound vehicles, such as rail vehicles (e.g. trams), but also to road automobiles, such as individual (private) passenger cars, commercial trucks or public transport vehicles (e.g. busses). Preferably, the primary side conductor arrangement of the generating device which produces the alternating electromagnetic filed is integrated in the track, road or parking area of the vehicle so that the electric lines of the primary side conductor arrangement extend in a plane which is nearly parallel to the surface of the road, track or parking area on which the vehicle may travel or may be parked.
Details of a preferred embodiment of the primary side conductor arrangement are described in WO 2010/031595 A2. For example, the current lines of the primary side conductor arrangement may extend along the track or road in a serpentine manner, i.e. some sections of the lines extend transversely to the travel direction and some sections of the lines extend in the direction of travel, thereby connecting the transversely extending sections. In particular, as illustrated in FIG. 5 and FIG. 12 of WO 2010/031595 A2, the primary side conductor arrangement preferably produces a magnetic wave which propagates in the direction of travel or opposite to the direction of travel. The speed of the wave is determined by the distance of the transversely extending sections and by the frequency of the alternating current which is carried by the different phases of the primary side electric conductor arrangement.
As also described by WO 2010/031595 A2, the receiving device can be located at the underside of a vehicle and may be covered by a ferromagnetic body, such as a body in the shape of a slab or plate. A suitable material is ferrite. The body bundles and redirects the field lines of the magnetic field and therefore reduces the field intensity above the body to nearly zero.
However, such a body of ferromagnetic material or, alternatively, a shield of electrically conducting material, cannot reduce the field intensity of the electromagnetic field to zero at locations sideways of the body or shield. In particular, while persons are entering or leaving the vehicle, they might pass the area sideways of the receiving device. Therefore, corresponding limits of the field intensity apply and must not be exceeded. For example, the International Commission on non-ionizing radiation protection (ICNIRP) has issued recommendations for corresponding limits.
Not only the primary side generating device, but also the secondary side receiving device of the vehicle produces an electromagnetic field during operation of the system for transferring the energy to the vehicle. If an electric voltage is induced in the electric conductor or electric conductors of the receiving device (which is sometimes called pick up), and if a corresponding electric current flows, this current produces an electromagnetic field.
Especially if the vehicle is provided with electric energy by induction while the vehicle travels, the gap between the primary side generating device and the secondary side receiving device is large compared to static systems, such as conventional transformers. Therefore, comparatively high frequencies of typically at least 1 kHz up to more than 100 kHz are chosen for the primary side alternating current and, therefore, for the produced electromagnetic field.
Persons, in particular passengers and staff, may approach the generating device during operation, in particular while a vehicle stands or approaches the location. At stopping areas where public transport vehicles regularly stop for allowing passengers to enter and to leave the vehicles, persons may even remain over longer periods of a time next to the generating device. Although the generating device is typically not operated continuously, operation may start at least shortly before the vehicle enters the location next to the person or persons.
It is an object of the present invention to provide an arrangement for providing a vehicle with electric energy, a method of manufacturing the arrangement and a method of providing a vehicle with energy by means of a receiving device which reduce the field intensity sideways of the generating device and/or sideways of the receiving device, in particular the exposure of persons sideways of the location where the vehicle stands or drives.
In particular, the generating device may have the serpentine (alternatively called: meandering) configuration described in WO 2010/031595 A2. Alternatively, the generating device may comprise at least one coil of an electric conductor. Other configurations are also possible, such as straight or slightly curved electric lines which extend in parallel to the path of travel of the vehicle.